Electromagnetic contactor with plunger armature



Nov. 13, 1951 A. P. CHARBONNEAU ET AL 2,575,095

ELECTROMAGNETIC CONTACTOR WITH PLUNGER ARMATURE Filed Deo. l5, 1944Patented Nov. 13, 1951 ELECTROMAGNETIC CONTACTOB WITH PLUNGER ARMATUREAllan P. Charbonneau and Frank J. Russell, Wauwatosa, Wis., assignors toCutler-Hammer, Inc., Milwaukee, Wis., a corpogation o! DelawareApplication December 15, 1944, Serial No. 568,318

2 Claims. l

This invention relates to improvements in electromagnetic contactors,and more particularly to contactors for use on airplanes and the like.

A primary object of the invention is to substantially reduce the size,weight and cost of contactors of the aforementioned character, while atthe same time improving the operating characteristics thereof.

Another object is to increase the eiliciency oi the magnetic system ofsuch a contacter to assist in attaining the results aforementioned.

Another object of the invention is to facilitate manufacture` of suchcontactors by simplifying the form and manner of assembling and/oradjusting the various parts thereof.

Another object is to provide an improved placement of the biasingsprings associated with the plunger and the contacter, whereby a maximumportion of the plunger may consist of iron.

Another object is to provide for use of a plunger having an integralflange whereby leakage ilux is substantially reduced and the pull in thesealed position is increased.

Another object is to so construct and assemble the partsl as to providefor sealing of both the flange and the plunger face, whereby a sealedpull of relatively high value is obtainable.

Another and more specic object is to provide a method of assembling theparts wherein a cup member is engaged by the plunger flange and pressedby the latter to the desired position within the coil shell as anincident to initial engagement of the plunger face with the stationarycore member.

Another object is to provide for utilization of said flange and said cupmember to effect determination of the length of the stroke of the magnetwithout requiring any further adjustment of said parts.

Another object is to provide a novel form of mounting bracket, a portionof which overlies and is attached to the core at the center of the coil;thus providing an increased thickness of magnetic material where theflux concentration is high.

Another object is to provide a novel sub-assembly of parts including ametal pin, a contacter carried thereby, and a bushing having threadedengagement with said pin whereby the pressure of said contacter againstthe stationary contacts may be preselected and thereafter maintainedsubstantially constant.

Another object is to provide novel means affording self-alinement of thecontactor with respect to the stationary contacts during normal use ofthe device.

Another` object is to provide novel means enabling removal and/orreplacement of the contactor and stationary contacts without inany- Wiseaffecting the initial adjustment of the switch parts.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate an embodiment of the inventionwhich will now be described; it being understood that the embodimentillustrated is susceptible of modification in respect of certainstructural details thereof and/or in respect of the manner of assemblingcertain of the parts.

In the drawings, Figure 1 is an enlarged central sectional view of acontacter constructed in accordance With our invention.

Fig. 2 is an actual size plan view of the device. Viewed from theleft-hand side of Fig. 1.

Fig. 3 is a view, partly in elevation and partly in section, of asub-assembly of certain parts i1- lustrated in Fig. 1, and

Fig. 4 is a transverse section on the line 4-4 of Fig. 3, showing themeans affording a drive t of the bushing with respect to the flangedplunger oi' Fig. 1.

In the drawings the numeral I0 designates a base molded from anysuitable insulating material. We prefer to employ either the molding material sold under the trade-name of Melmac or the molding materialsoldunder the trade-name oi' Bakelite When base IIJ is composed ofBakelite We prefer to mold or embed in one i'ace thereof a pair of likesheet steel pole pieces Il, Il which define the major portion of thelength of the bottom wall of a transverse groove; the plane of whichbottom wall is indicated by numeral I2. The adjacent ends of pole piecesH are spaced from each other a distance only slightly greater than thediameter of a circular opening I3 formed in base I0, and the outer endsof said pole pieces are spaced only slightly from .the opposite ends I4and i5 of said base. Said pole pieces Il are preferably provided atopposite sides thereof with upstanding iiange portions (not shown) whichextend a distance approximately equal to the diameter of the contacttips and along the sides thereof. The outer edges of said iiangeportions are preferably coplanar with the outer surface of said base.Said pole pieces therefore act in a known manner to assist inextinguishing any arcs which may be formed.

Each of the two stationary contacts comprises a at and relatively thickpunched plate I6 of metal of good electrical conductivity (preferablycopper) having rounded ends Il and i8, respecthreading of each shank 2|)into an opening' i9 the material of plate I5 is ring-staked around saidopening I9, as indicated at 22, to lock said l parts against relativemovement, and to provide low resistanceelectrical contact.

Pole pieces Il are provided respectively with openings 23 and base I0 isprovided with openings 24 respectively alined therewith to provide forslidable insertion of shanks 20 therethrough. A screw has its threadedshank 25 freely penetrating alined openings in base I0 and in therespective pole piece Il and taking into a tapped opening 26 in eachplate I6 to rigidly secure the latter and its associated terminal boltto said base. The head 21 of each screw is preferably accommodatedwithin a countersink or recess in base I9, and a lockwasher 28 ofsuitable form is also' preferably positioned between the screw-head andthe bottom wall of the recess. If desired the remainder of each recessmay be filled with a suitable wax or cement' (not shown) to additionallyrestrain the screws and insulate the heads 21 thereof.

Prior to assemblyfof each plate I6 with respect to base I0 asaforedescribed said plates have attached thereto in any suitable mannerthe silver base contact tips designated by numeral 29. In practice it ispreferred that plates i6 be prepared in the manner disclosed in PatentNo. 2,361,089, granted October 24, 1944, to I. W. Cox, and that asuitable metallic composition in powder form be united therewith bymolding Vin the manner disclosed in said patent.

The shank 20 of each terminal bolt has threaded thereunto a nut 30 whichassists in rigidly at-v taching the same and its associated plate i6 tovbase Ill;v a lockwasher 3| of well known form preferably beinginterposed between said nut 30 and base Ill. A second nut 30 is alsothereafter threaded onto each shank 20 to act as a clamp or bindingelement for thebared end of a circuit wire (not shown) which ispreferably located between a metal washer 32 and the inner nut 3U.

' A split lockwasher 33 is preferably interposed between washer 32 andthe outer nut 30 to prevent accidental loosening of the latter.

The operating coil of the contactor is designated by numeral 34, saidcoil being wound in a known manner vand impregnated with a suitablematerial to insure against failure thereofy i when in use. All surfacesof coil 34 are provided with a. suitable insulating covering, asindicated by numerals 35, 36, 3:1 and 38. Said coil as thus I coveredispositioned within a seamless cupshaped shell 39, preferably formed ofsteel; said or slightly enlarged portion 40, whereby a shoulder 4| isprovided.

A relatively thin tube 42 of non-magnetic material such as brass isadapted to iit snugly within the central passage or opening in Icoil 34;said shell having at its open end an outwardly offset ing bolt, whosethreaded shank 4l!Y takes into recess ,45. Portion 46 of said boltils/accommodated within alined openings 48 and 49 respectively formed inthe end wall of shell 39 and in the arm 50 of a supporting bracket.Another and substantially parallel arm 5I of said bracket has an annularflange portion 52 formed thereon to accommodate that end portion ofshell 39 which is of smaller diameter,` and to snugly ilt against theenlarged portion 40 and shoulder 4| aforementioned. Said special bolt`is provided with a head 53 of hexagonal or other polygonal form; alockwasher 54 being interposed between the same and bracket arm 50. Thusupon tightening of said bolt the shank 41 draws core member 43 intodirect engagement with the inner surface of the end wall 55 of theshell; the metal tube 42 being simultaneously moved therewith to portion40 of the shell; said cup washer having an outer annular flange 58adapted to slidably t within said enlarged portion, and an inner,relatively shorter, annular flange 59 adapted to surround at least aportion of the projecting end of tube 42.

The plunger of the contactor is composed of magnetic material, the samehaving a substantially cylindrical main portion 60 and an integralannular flange 6I at the outer end thereof. As shown the end 62 of theaforementioned core 43 is preferably of substantially cone-shape, andthe adjacent end of plunger 60 is correspondingly of hollow cone-shape,as shown at 63 to t snugly thereag'ainst. The arrangement is such thatflange 5| overlies the upper edge of the inner flange 59 on the cupwasher, so that when plunger 60 vis pressed inwardly until the surface63 seats firmly against the cone-shaped surface 62, the flange 6i willhave, simultaneously engaged flange 59 to force the cup washer 51 thedesired distance into the metal shell. Ir this manner simultaneoussealing of surface 63 with surface 62 and of flange Sivagainst ange 59may be insured. After cup washer 51 is thus properly positioned, suchpositioning may be made rigid and permanentl in any suitable manner,such' as by welding or soldering said cup washer and shell to eachother.

The bridging contactor comprises a flat punched plate 66, preferably ofcopper; said plate having circular tips 29, 29 like thoseaforedescribed. rigidly attached topposite ends thereof. Said contactortips 29 are properly spaced (see Fig. 1) for alinement thereof with tips29 of the stationary contacts. Plate 66 preferably has its ends 61 and68 rounded to conform substantially with the contours of the tips29mounted thereon. Said plate 66 is also provided with a centralcircular opening 69', within which an insulating bushing 10 ispositioned; said bushing 10 being pref-y erably molded in situ. Bushing10 is preferably composed of Melmac," which is characterized by itseffective resistance to damage by heating or arcing. Bushing 10 hasformed integrally therewith the annular flanges 1i and 12, which overliethe respective opposite faces of plate 66 aroundv said opening 69. Arecess 13 is formed in bushing 10 to accommodate the substantiallycorrespondingly shaped cup washer 14, which is pref- 7 5 erably formedof brass.

A coiled compression spring 15 has one end seated within cup washer 14;a metal pin 16, preferably of steel, penetrating alined central openingsin bushing and cup washer 14, and having an annular groove '|1 formedtherein adjacent one end thereof. A horseshoe-shaped washer 18 ispressed into groove 11, and a'metal cup washer 19 is positioned upon pin16 to surround washer 18 and prevent accidental lateral displacementthereof; the other end of spring abutting against the exterior surfaceof cup washer 19.

The outer surface 80 of bushing 10 is preferably in the form of asegment of a sphere, for cooperation with the correspondingly shapedconcave bearing surface 8| upon a molded hollow insulating member 82,also preferably composed of Melmac. Member 82 has a relatively shortinner flange 83 and a relatively longer outer flange 84, between whichone end of a coiled compression spring 85 (Fig. 1) is adapted to seat.Prior to assembly of spring 85, however, the threaded end portion 86 ofpin 16 is screwed into the internally threaded portion 81 of a bushing88, preferably machined from a steel rod. The edge of the aforementionedflange 83 is adapted to abut against the adjacent end of bushing 88,whereby upon a predetermined degree of turning of pin 16 relatively tobushing 88, spring 15 will be compressed to a degree to insure thedesired pressure of the bridging contactor against the stationarycontacts when all of the parts are nally assembled. In other words, theadjustment of pin 16 with respect to bushing BS is merely such as toprovide the desired degree of compression of spring 15, as measured inpounds. When the desired adjustment has been effected, a Quantity ofmolten solder 89 or the like is dropped into the end of bushing 88 tooverlie and surround the reduced end portion 90 of pin 16 to restrainsaid parts against further movement relatively lto each other. Bushing88 is provided with an end portion 9| of reduced external diameter,toward which the intermediate portion 92 is tapered as shown. The mainbody portion of bushing 88 has four equally spaced longitudinal groovesformed therein by rolling or otherwise in such manner that four pairs oflongitudinal fins or proiections 93 are provided (Figs. 3 and 4). Fins93 are of such lateral dimensions as to provide for a force t of bushing88 into a recess 94 in the outer end of bushing 60; bushing 88 beingpressed inwardly to a degree to afford the proper wear allowance ofbridging contactor 66.

A relatively thin walled molded insulating cover member 95 is providedto house or enclose contactor 66; said member 95 having a pair ofopenings formed therein (one on each side of the hollow dome orextension 96, Fig. 1) Base I0 has a pair of upstanding lugs formedintegrally therewith on opposite sides of the groove I2; one of saidlugs being shown at 91 in Fig. 1. Said lugs serve to guide thereciprocating movements of contactor 66, and each of said lugs hasmolded therein and projecting outwardly therefrom a threaded stud (notshown) respectively penetrating said openings in cover 95; a pair ofnuts (not shown) being threaded onto said studs to clamp cover 95 inproper position upon base I0.

The aforementioned bracket arm 5| is provided with perforations (Fig. l)to be alined with the tapped recesses in metal inserts 98, 98 in baseI0; suitable screws 99 and lock-washers |00 being provided for clampingsaid bracket arm and its associated parts to base I0.

The connecting portion I0| of the bracket is provided with openings |02and |03 to accommodate the shanks of suitable mounting bolts or screws(not shown) for attachment of the complete device to a panel or othersuitable support.

The aforementioned arm of the supporting bracket is provided with arelatively small opening |04 which is adapted Yto accommodate a raisedportion or boss |05 formed upon the end wall of shell 39, wherebyrelative rotation of the shell and bracket is prevented. Although saidbracket is formed of relatively thin sheet metal, the same is providedwith suitable embossed ribs and llets, as shown, to strengthen the sameand resist distortion thereof when in use.

As shown in Fig. 2, base I0 is provided with an integral extension |06having a downwardly offset ledge |01, which is adapted to accommodate,in a substantially flush relationship, the lateral extensions of theinsulating members or plates 31 and 56 (Fig. 1), such extension of plate31 being designated by numeral |08 in Fig. 2. Interposed between saidextensions are a pair of relatively thin copper ribbons, Shown in dottedlines at |09 and ||0; said ribbons being attached to opposite ends ofthe Wire of coil 34 and having enlarged ends in the form of eyeletswhich are upset over the outer surface of plate 31, as indicated at and||2 in Fig. 2. Screws I|3 and ||4 have their shanks extending upwardlythrough alined openings in base extension |06, plates 56 and 31 (andeyelets III, H2), and one or more nuts |I5, IIS are associated with saidscrews to clamp the parts in position and to provide for attachment ofsuitable terminal wires. If desired a bus member II'I may be interposedbetween screw ||4 and one of the screws 99 t0 provide for grounding ofthe coil circuit.

We claim:

1. In an electromagnetic contactor, in combination, a cup-shaped shellof magnetic metal, an operating coil positioned within said shell, acore member of magnetic metalpositioned Within said coil, a cup-shapedmetal member positioned within the open end of said shell and rigidlysecured to the latter to retain said coil in assembled position, saidshell having an external annular` shoulder formed thereon adjacent saidopen end thereof, a bracket of magnetic metal having a pair ofsubstantially parallel arms and a connecting portion, one of said armshaving a relatively large opening formed therein to slide onto saidshell and seat against vsaid shoulder, said arm having perforatedintegral lateral projections, a molded insulating base formed toaccommodate the open end portion of said shell and against which saidarm is adapted to seat, screws penetrating said perforations and havingthreaded engagement with said base to clamp said parts in assembledrelation, the other arm of said bracket overlying the other end of saidshell to provide an increased thickness of magnetic material where theflux concentration is high, said last mentioned arm and said shellhaving alined openings formed therein, a securing screw penetrating saidopenings and having threaded engagement with said core to rigidly securethe latter and said last mentioned arm to said shell, and said brackethaving means associated therewith to provide for attachment thereof to asuitable support.

2. In an electromagnetic contactor, in combination, a cup-shaped shellof magnetic metal, an operating coil positioned within said shell, acore member of magnetic metal positioned With- 7 in said coil, acup-shaped metal member positioned within the open end of said shell andrigidly secured to the latter to retain said coil in assembled position,said shell having an external annular shoulder formed thereon adjacentsaid open end thereof, a bracket of magnetic metal having a pair ofsubstantially parallel arms and a connecting portion, one of said armshaving a relatively large opening formed therein to slide onto saidshell and seat against said shoulder, said arm having perforatedintegral lateral projections, a molded insulating base formed toaccommodate the open end portion of said shell and against which saidarm is adapted to seat, screws penetrating said perforations and havingthreaded engagement with said base to clamp said parts in assembledrelation, the other arm of said bracket overlying the other end of saidshell to provide an increased thickness of magnetic material where theflux concentration is high, said last mentioned arm and said shellhaving alined openings formed therein, a securing screw penetrating saidopenings and having threaded engagement with said core to rigidly securethe latter and said last mentioned arm to said shell, said brackethaving means associated therewith to provide for attachment f thereof toa suitable support, said cup-shaped metal member having an openingformed therein and an integral iiange extending axiallyoutwardrthereabout, a plunger of magnetic metal slidable within saidlast mentioned opening and having an inner end adapted to seat againstsaid core, said plunger having a laterally extending integral flangeoverlying and engaging the ange on said cup member when said plunger isin its inner extreme position, and spring means associated with saidplunger externally of the latter to normally bias the same to its outerextreme position.

FR J. RU.

REFERENCES @FEED The following references are of record in the ille ofthis patent:

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